1. Technical Field
Dynamic stabilization of the spine.
2. Description of Related Art
Physical discomfort from degenerative conditions of the spine such as disc disease, spinal stenosis, and spondylolisthesis affects a large segment of the population. Symptoms are related to compression of spinal nerves or nerve roots and may include intermittent neurogenic claudication, pain in back or legs, numbness, weakness and loss of balance. Conservative treatment may include rest, physical therapy, bracing, anti-inflammatory medications, analgesics, local anesthetic blocks and epidural steroid injections.
Treatment by spinal fusion is frequently offered to patients who suffer from these conditions. However, fused vertebrae have been associated with loss of mobility and deterioration of adjacent discal architecture due to increased strain and forces at such discs. Dynamic spinal stabililization of the spine is a treatment modality intended to overcome such deficiencies. Dynamic stabilization allows adjacent vertebrae to be stabilized through the use of, e.g., articulating structures, compressible structures and the like, to allow relative movement of adjacent vertebrae which are supported by such structures. In this manner, the aforementioned disadvantages of rigid fusion are avoided.
Surgical decompression with or without fusion is a standard surgical treatment for patients with moderate to severe lumbar spinal stenosis. Cervical, thoracic, and/or lumbar interspinous process decompression (IPD), also known as interspinous distraction or posterior spinal distraction, is a form of dynamic stabilization that has been proposed as a minimally invasive alternative to laminectomy and fusion. In IPD an interspinous distraction implant is inserted between the spinous processes through a small (e.g., 4-8 cm) incision. The implant is intended to restrict painful motion while enabling otherwise normal motion. The implant forms a wedge that enlarges the neural foramen, decompresses the cauda equina and acts as a spacer between the spinous processes to maintain the flexion of the spinal interspace. This reduces pressure on the exiting nerves and allows for relief from sciatica and oftentimes back pain as well. Due to the off-loading of the posterior spinal disc, small tears and herniations may improve as well.
Many implants designed for dynamic stabilization are inserted using open procedures. Minimally invasive surgical techniques are used to minimize trauma to a patient by reducing the size of a surgical wound. A percutaneously inserted interspinous spacer can optimize patient outcome by further minimizing the surgical incision and accompanying tissue damage. US Patent Appln. Pub. No. 2010/0100183, filed Sep. 15, 2015, incorporated herein by reference in its entirety, is directed to a swellable interspinous stabilization implant. In embodiments, the implant has a first configuration of reduced size such that it can be inserted into a patient in a minimally invasive manner. Once inserted to an application point within the patient, the implant expands in size to dynamically maintain the adjacent spinous processes in beneficial alignment.
There is continuing need for improved methods and devices for stabilizing compromised spinal architecture.